You can reserve 31 days in advance. The slots are open at 6 pm (Japanese time).If you are a bigger group I would recommend you to book early. You can cancel the table for free a day before till 10 pm (by phone!).

They have A-C seats and D seats. D Seats are the seats at the counter (long table in the middle). If you are alone you have to choose a D Seat, if you are a group from 2-4 persons, you can choose any other seat.